Membrane technology applied to steel production: Investigation based on process modelling and environmental tools

Abstract

A model of a two-stage membrane separation process for CO2 capture from iron and steel industry as well as a model for gas-liquid absorption using methyl di-ethanol amine are investigated and compared in the present paper. In order to compare these CO2 capture technologies, the following processes have been investigated: i) two air separation technologies based on distillation and membranes in order to produce the oxygen used in the basic oxygen furnace; ii) a plant for steel production using basic oxygen furnace technology and iii) two plants for CO2 capture based on the above-mentioned technologies. The annual production capacity of the steel mill is 4,000,000 tones. An O2 separation rate of about 96% was obtained in the distillation technology, and about 33% in the membrane technology. The CO2 capture rate obtained in the membrane case is higher than that obtained using methyl di-ethanol amine (93.97% vs. 89.97%). From a technical standpoint, the simulation results lead to the conclusion that membrane-based technology can be a suitable alternative for CO2 removal for steel production. O2 separation using membrane involves higher air flow-rates, lower O2 separation rate compared to cryogenic air distillation (e.g., 33.15% vs. 96.47%) and lower O2 purity. The cases were also evaluated from an environmental point of view using the Life Cycle Assessment methodology. The environmental evaluation shows that membrane technology can lead to lower environmental emissions if membrane production is based on benzene derived from toluene hydrodealkilation, and chlorine and sodium hydroxide are produced using mixed technologies.